Answers to Tutorial A on AAA EVAR PDF

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Meds13008 Vascular Sonography

AAA

General Sono - Even patient comes in query gall bladder pain, fatty meals. What sort of documentation. Case study 1: Presentation M62- man presented with spontaneous pneumothorax, lumbar pain and pain in the lower limbs. Biochemical investigations revealed a low hemoglobin and hematocrit. Plain abdominal radiographs revealed prevertebral calcifications at the mid-abdominal level. An abdominal ultrasound was performed which revealed left hydronephrosis and the following findings.

Male, 62- Both are risk factors for AAA. Risk factor- pain in lower limbs. Low haemoglobin and haematocrit. The haemocrit measures the volume of rbc compared to the total blood volume (plasma). What is the difference?

Hemoglobin (Hb) is the protein contained in red blood cells that is responsible for delivery of oxygen to the tissues. The hematocrit measures the volume of red blood cells compared to the total blood volume (red blood cells and plasma).

Image: Transverse image of the central retroperitoneum. The echogenic vertebrae can be seen shadowing behind it. Upper lumbar vertebra. Usually the landmark of where the vertebrae is. An aorta is the circular echogenic structure with an echogenic lumen. On this particular patient, the aorta is not intact. Halo effect. On the right hand, no definitive line to the aorta. Very suspicious AAA. The fact it has got low haemoglobin and haematocrit. Loosing blood somewhere. There is thrombus within the aorta. Description: A large heterogeneous prevertebral retroperitoneal mass is seen on the left side of the abdomen. This mass was in close proximity to the abdominal aorta and demonstrated pulsations

Image on left : Another scan at the mid-abdomen level

Description: A heterogeneous mixed echogenicity mass is seen again in this view, in the pre-aortic region

\ See the vertebrae, upside down moon. Bright echogenic edge with echo-lucent centre. Very ill defined mass at the pre-aortic region.

Image left: Another scan at the midabdomen level

Description: The pre-aortic mass displays cystic component. Posteriorly, few linear strongly echogenic specs are noted, which show posterior shadowing and possibly represent calcifications.

Adventitia not well delineated at all. Cystic component of the mass. Posterior to the cystic structure, there is echogenic structure which is linear. Posterior shadowing . not vertebrae because vertebrae is half moon shaped. This linear echogenic structure may represent calcification

Image on Left : Color Doppler ultrasound, transverse image of the central retroperitoneum

Description: The level of the communication of the retroperitoneal mass with aortic dilatation is observed

Flow is swirling around. No aliasing. Going from one direction to another without changing a great degree in its velocity. Outside of the lumen flow is seen coming out. Blood flow leaking outside the lumen.

Final Diagnosis Large retroperitoneal hematoma with associated aortic abdominal aneurysm rupture Run probe over lower abdomen. Find anechoic areas due to blood pooling due to the rupture. All 3 walls of the artery are involved in the aneurysm. 1.5 time

Discussion Abdominal aortic aneurysm is a segmental dilatation of the aortic wall that causes the vessel to be larger than 1.5 times its normal diameter or that causes the distal aorta to exceed 3 cm. This can continue to expand and can rupture spontaneously causing exsanguinations and even death

[1].

Abdominal aortic aneurysm rupture is an important cause of unheralded deaths in people older than 55 years. The risk factors for aneurysm rupture are: the increased initial or the rapid growth of the aneurysm diameter, smoking, advanced age, male sex, lower forced expiratory volume, chronic obstructive pulmonary disease, hypertension, and family history. Abdominal aortic aneurysm rupture is more frequently produced in the left side

[1, 2].

Clinically abdominal aortic aneurysm rupture may be an incidental discovery or the patient could present with abdominal, back or flank pain [1, 2]. X-Ray findings: A curvilinear calcified rim often to the left of the midline is apparent on some plain abdominal radiographs. Mural calcification can be radiographically unapparent and lead to a false-negative finding in as many as half of small abdominal aortic aneurysm

[1, 3].

Unlike most other modalities (aortography, CT, MRI), abdominal ultrasound can be performed expeditiously and at the bedside. With partially encapsulated hematoma, a hypoechoic or anechoic para-aortic space-occupying lesion may be detected. Color-flow Doppler can aid in detecting the site of leak or extravasations, although adjustment to low-velocity scales may be necessary to register leaks with low flow rates

[3, 4, 5].

CT findings that indicate possible abdominal aortic aneurysm rupture include soft tissue hyperdensity outside the aortic wall, an indistinct aortic wall, thinning or fracture of a calcified aortic wall segment, penetration of a hematoma into the leaves of the mesentery, or extravasation of contrast into the psoas muscle or retroperitoneum, enlargement or obscuration of the psoas muscle, and anterior displacement of the kidney

[1, 5, 6].

MRI is a valuable alternative to CT in patients with renal insufficiency in who contrast material–induced nephropathy is a concern. MRI is also helpful in further delineating the aorta in the context of a large retroperitoneal collection that obscures the borders between adjacent structures, as well as laminated clot or atherosclerotic debris on the aneurismal wall

[7].

Angiographically a circumscribed extraluminal contrast enhancement is seen. In case of leaking aneurysm the frank extravasation of contrast material with poor washout is observed. This is rarely demonstrated because the patients are typically in unstable condition and are transported directly to the operating room

[1, 3].

Abdominal aortic aneurysm rupture, symptomatic expansion, or sentinel leak is a surgical emergency. Endovascular reparation with graft placement with or without hypo gastric or internal iliac artery embolization represents a surgical option

[1, 3]

Case References1. Tan WA, Makaroun MS. Abdominal Aortic Aneurysm, Rupture; http://www.emedicine.com/radio/topic2.htm 2. Frank A. Lederle. Ultrasonographic Screening for Abdominal Aortic Aneurysms; Annals 2003;139:516-522. 3. Radvany MG, Seguritan V. Abdominal Aortic Aneurysm, Diagnosis; http://www.emedicine.com/radio/topic1.htm 4. Badea RI. Aorta. In: Dudea SM, Badea RI. Ultrasonografie vasculara, Ed. Medicala, Bucuresti 2004, 353-362. 5. Bendick PJ, Zelenock GB, Bove PG, Long GW, Shanley CJ, Brown OW. Duplex ultrasound imaging with an ultrasound contrast agent: the economic alternative to CT angiography for aortic stent graft surveillance. Vasc Endovascular Surg. 2003 May-Jun; 37(3):165-70. 6. Giannoni MF, Palombo G, Sbarigia E, Speziale F, Zaccaria A, Fiorani P. Contrast-enhanced ultrasound imaging for aortic stent-graft surveillance. J Endovascher003 Apr; 10(2):208-17. 7. Tatli S, Lipton MJ, Davison BD, Skorstad RB, Yucel EK, MR Imaging of Aortic and Peripheral Vascular Disease; RadioGraphics 2003; 23:S59–S78.

Case study 2 AAA Review normal anatomy A

B ? Vessel?

Ao at level of what vessel? Why may this level be

? Name this vessel? How does involvement of this vessel change the management of a patient with an AAA? Once the length of an AAA involve the origin of one or both the origins of the renal arteries, immediate surgical intervention become imperative. What should the maximum measurement of a normal aorta be? Answer: Normal; Ao should be no more than 3cm in diameter at any point. The normal aorta typically tapers as it approaches the bifurcation. If you were working in a clinical department and Maria was your supervisor, would she consider this image as a satisfactory documentation of the proximal Aorta?

No, Justify your answer. The Aorta as it passes from the thorax through the diaphragm and into the abdomen has not been imaged. This potentially may exclude visualisation of distal component of a thoraco-abdominal Aneurysm from being diagnosed. Distal Aorta: Are the Iliac vessels normal in this image below? Justify your answer.

ANSWER:

Yes. Sonographically image is considered normal as No dilation No evidence of wall changes thickening Nor AS have been displayed. What probe manipulation has the sonographer performed? At level of BIF transducer has been moved to patient RT then angled medially towards AO to visualise both R CIA and LT CIA. Has the following Aortic AP measurement been made correctly?

Answer: NO The measurement should be taken OUTER wall to OUTER wall and if you look closely at the most anterior caliper it has been place within the Aortic lumen (inside wall)

You are on your year 3 placement and the next patient is referred for a scan to rule out or confirm an AAA. Before you both enter the roo to perform the scan your supervisor quizzes you on the requirements that need to be assessed. Can you tell the supervising sonographer the criteria for the diagnosis of an AAA? Answer: Focal dilation of Abdo Ao > 3cm an increase of the Ao diameter 1.5x the normal expected diameter. Extra info:- = Ratio of infrarenal to suprarenal Ao diameter of > 1.2 Aneurysms can be defined by:

location: Suprarenal Juxtarenal Infrarenal= 90% of AA Shape: Fusiform= most common configuration Saccular Hourglass (Bi-lobed) Associated with: AS changes Plaques +/- calcification Mural thrombus Label the components of this sagittal image of an AAA and state the shape represented (type of AAA)....